Musical instrument.



J. P. KELLY.

MUSICAL INSTRUMENT.

APPLICATION FILED APR,29,1911

1,078,627, Patented Nov. 18. 1913 Jams 13'. KELLY, or'PI'TTsrIELn;MASSACHUSETTS.

musroar. INSTRUMENT;

specification of Letters Patent.

Patented Nov. 18', 1913.

Application fileaa ru 29, 1911. Serial No. 624,237.

To all whom it may concern:

Be it known that I, JOHN F. KELLY, a citizen of the United States ofAmerica, residing, a-tPittsfield, in the county of Berkshire and Stateof Massachusetts, have inventednew and useful Improvements in MusicalInstruments, of which the following is a specification;-

Thisinvention relatesto improvements in means or devices-for producingmusicaltones or. sounds of a single pitch.

It consists-,,in.genera l of a metallic member' 01? body of a suitablesize and thickness that is adapted to. respond to the electromagneticinfluences of electrical currents. Such abody, therefore, must becomposed of some substance that possesses magnetic properties, as iron,steel, on some alloy that possesses them It isa wellknown. fact inelectrical science that sheets and rods ofironor'steel will: becomehighly magnetized, either temporarilyor permanently, when brought withinthe field of an electric current, and that electromagnets possess theproperty of strongly attreating or repelling such magnetic substances.With these facts in mind, I have conceived thev idea of causing platesof magnetic substances to be vibrated by the periodic attraction ofelectromagnetic devices to produce musical sounds It is also a wellknown fact that the surface of thin plates or disks of. metal or othersubstances, as glass, when set into vibrationby means of the stretchedstring. of a bow do not vibrate at all points; or, in other words, thereare nodal lines or points at which no vibration occurs. These nodallines are known as Chladnisrings and are notas a rule symmetrical inform with respect to the center of the plate,.as for example the nodallines onthe upper surface of a circular late with free unsupported edgesare not always concentric with relation to its geometric center, but aremore or less distorted from the true circle; in fact, they are oftenelliptical in form. Such irregular arrangement of the nodalili'nes isdueto the uneven or non-unifoz' m anrangement of the molecules of the ofthe'molecules they do not conform to the theory. 1

One object, therefore, of my improvement 18 to produce a sonorous ormusical producing plate in which the nodal line may be fixeda-ndpractically all others destroyed, that is to say, to produce in such abody a result which would be producedif the molecular arrangement oftheimolecules in the body were homogeneous throughout- Another object isto produce astructure that will only respond to a definite number ofmagnetic vibrations, and thus prevent its being vibratedby a neighboringbody in which magnetic disturbances are present.

With these objects in view, reference is made'to the accompanyingdrawings, forming apart of this specification, in which,-

Figure 1 1s a plan view of a circular plate representing the soundproducing body inwhich a number of radial slits are formed which extendfrom the free edge toward the center but not far enough to intersectFig. Qis a sectional side view of Fig. 1 showing. electromagnetic meanslocated below the plate with one of its poles in close proximitythereto; also a ring surrounding the electromagnetic means and attachedto the lower side of the late. Fig. 3 is a modificationof theelectromagnetic devices for attracting the plate and comprises atransformer construction. Fig. 4' is afurther modification of theelectromagnetic device and comprises a simple make and break device inthe circuit which surrounds thecore of the electromagnet, and Fig. 5 isa modification of the electromagnetic device in which the plate itselfis employed to open and close the circuit, Fig. 6 is a modification ofthe structure of the plate in which the nodal ring element is omitted,the plate being slitted so as to produce an integral ringof metaltherein,

Referring to the drawings in detail, a designates the sonorous platewhich is to )roduce the musical sounds when the same is caused tovibrate. This plate is composed of some highly magnetic material, as ronor steel, or possibly some mag-netizablc alloy as shown at b, whichextend far enough to:

ward the center sothat a fa-irly narrow neck of.metal is left in thebody, as indicated at a,

but the center portion of the plate is left unslitted in Order toafi'o-rd enough metal to permit or allow the plate to vibrate as a onepiece member or body, and not as a reed element. The electromagneticdevice which is designated at d powerfully attracts the a designates aring member that is provided with a beveled or knife edge 7' which issecured to the under side of the plate a in some suitable manner, as bybrazing or sol dering. The diameter of the ring, as measured at thebeveled edge j, is such as to a 'ee with the diameter of the nodalcircle 0 the plate, or the circle at which there is practically novibration of the molecules. The radius of this nodal circle ispractically 0.68 of the radius of the disk, as experimentallydetermined.

As stated above, the nodal lines, of a vibratory plate, by reason of thenon-homogeneity of the plate, do not always arrange themselvesconcentric with the center. By means of the-rigid ring 6, I have foundthat the nodal circle of the plate can be made to follow or conformpractically to a true circle when the plate is vibrated to roduce amusical sound. By using the rigld ring 2' a truly circular node in theproper position is secured and by slitting the dis and employing acentral excitation the residual efiects due to non-homogeneity of thematerial is reduced. The reed-like elements by the slits being tiedtogether at t e center of the disk and to the nodal ring 2' (the pointof least vibratiom) causes the amplitude of each element to vibrate thesame amount. The extreme amplitude of vibration is therefore the samefor all, and the whole set of reed-like elements must vibrate in unison,or not at all. Cross vibration of each reed element of course isprevented by havin a large enough number of these elements until thedesired result is secured for the whole disk. As a means of producinthis vibration, the electromagnetic device sown herein is employed. Itwill therefore be seen that when this plate is attracted by means of thecore mem er 6 being) energized, it will be laced in a state of v1ration, the center an outer portions moving or vibrating inoppositedirections. The use of the mug 2', and the slitting of the disktherefore, serves to obroduced tain two definite resultsfirst,' thenodal circles will be confined to one, all of the others beingpractically destroyed; and, second, the plate is made to act as if themolecules were arranged in a homogeneous manner through out, whereby thenodal line which is formed is practically a true circle.

-For producing a change in the magnetic condition of the core member 6,I do not limit myself to the device shown in Fig. 2, wherein currentsfrom an alternator of suitable frequency are employed in the windings f.In Fig. 3, a. transformer or induction coil is is employed between thealternator and the windings of the electromagnet. In Fig. 4 a battery mis used and a simple make and break device n is used to open and closethe circuit to the windings f. In Fig. 5, the plate itself is caused toopen and close the circuit, and one way of accomplishing this is toprovide the plate with a finger 0 which is adapted to engage theadjustable screw p. 9 indicates a switch device to which one ter-' minalof the battery 1' is connected, its other terminal being connected tothe winding f, and the other terminal of the winding to the ring a,which completes the current through the plate to the finger 0.

In the device which I employ, the dimensions of the ringz' is such thatonly one nodal circle is produced, or under consideration, and thus onlya single tone is produced by the. plate.

On account of the plate being slitted to cause the plate to vibrate as ahomogeneous body, and the use of the ring 2' to limit and confine theproduction to only one nodal ring, it is possible to employ severalplates in close proximity to each other without there being any mutualdisturbance. It is therefore possible to employ or group a series ofsuch plates together to construct a musical instrument that will furnishall of the musical notes desired; as for example, the'substitution ofthese plates for pipes in an organ. 11

In Fig. 6 the plate (1, instead of having continuous slits cut therein,as shown at b, Fig. 1, is formed with a break leaving a narrow neck ofmetal 8 interposed between the adjacent ends of the long and short slits1 5 t and to. This neck of metal is located on the nodal line or circleand coincides with the diameter of the ring element 2' shown in theother figures. The formation of the plate w, shown in Fig. 6, producesthe same results as set forth above under the construction shown in theother figures, that is it causes the plate to vibrate as if it were ahomogeneous mass throughout. The series of neck portions 8 are, ineifect, a ring element.

What I claim, is 1. In a device to roduce a musical tone, thecombination 0t a vibrating member, rigid means in direct contact withand secured thereto and positioned to coincide with a nodal line of themember, and means to vibrate the member, whereby said member may vibrateabout the rigid means as a support.

2. In combination, a sonorous member which is capable of producing asingle tone, said member comprising a single, slitted plate, means todefinitely position a nodal line in the plate, and devices to vibratethe plate. 4

3. In combination, a magnetizable sonorous member which is capable ofproducing a single tone, said member comprising a slitted plate, meansto definitely position a noda line in the plate, and electromagneticdevices to vibrate the plate.

4. A sound-producing device, comprising a slitted vibratory member,rigid means secured to said member to define the principal nodal line insaid member, and means to vibrate the member.

5. An electromagnetic sound producing device comprising a magnetizableplate, a rin attached to the plate and coinciding wit a nodal line, andmagnetic means to vibrate the plate.

6. .An electromagnetic sound producing device. comprisin a slittedmagnetizable plate, a ring attac ed to theplate and coinsiding with anodal line, and magnetic means to vibrate the plate.

7. In combination, a vibratory magnetizable 'plate, a ring elementprovlded with a knife-edge and secured thereto, and an electromagneticdevice to vibrate the plate.

8. An electrical monophone device comprising a slitted plate, a ringsecured there to to position a nodal line therein, and anelectromagnetic device to vibrate the plate, whereby the plate willvibrate in unison with the said device.

JOHN E. KELLY.

Witnesses: Y

K. I. CLEMONS, HARRY W. Bowen.

